Ammoniagenesis was studied in confluent cultures of the LLC-PK1 renal epithelial cell line. It was found that ammonia production was strictly dependent on the extracellular glutamine concentration. LLC-PK1 cells respond to metabolic acidosis. LLC-PK1 cells exhibited an increase in ammonia production and glutamine consumption with decreasing pH of the culture medium. In order to study the relationship between ammoniagenesis and gluconeogenesis attempts have been undertaken to isolate LLC-PK1 cells capable of gluconeogenesis.